The energetically expensive input to the Haber-Bosch process is hydrogen. At present hydrogen is predominantly manufactured by steam reforming of fossil fuels,

The energetically expensive input to the Haber-Bosch process is hydrogen. At present hydrogen is predominantly manufactured by steam reforming of fossil fuels, which produces CO2 as a byproduct. Hydrogen can also be produced cleanly by water electrolysis powered with clean electricity. I actually think that Haber-Bosch plants will predominantly use clean electrolytic hydrogen before farm machinery becomes predominantly electric. Farm machinery has a very slow replacement cycle. Some of my farming relatives are still running diesel powered machines built in the 1930s.